[clang] [clang][Sema] Track trivial-relocatability as a type trait (PR #84621)

QrczakMK wrote: I think that if Clang chooses to support both variants of the type trait, it should provide both variants of `[[clang::trivial_abi]]`, so that a type like `std::unique_ptr` is trivially relocatable including assignment (and can be annotated as such), while a type like `std::tup

[clang] [clang][Sema] Track trivial-relocatability as a type trait (PR #84621)

QrczakMK wrote: It would be great to see progress in this. Lack of detection of trivially relocatable types costs extra memory allocations in my project, and I feel uneasy carving a manual exception for `std::unique_ptr`. https://github.com/llvm/llvm-project/pull/84621